Although R&D work on an ultra-short radius level drilling tools has gained a lot of results, there are still many technical problems. In drilling work for inclined interval and level interval, same kind of drilling tools are being used at present. During level interval drilling after finishing inclined interval, an orientation is difficult to be controlled, easy to cause deviation. The earlier developed drilling tools have the shortcoming that structuring members of flexible drill pipe are fixed up or connected together by way of clasping and welding, which leads to being difficult in assembling and time-consuming in service. Besides, drilling fluid is being delivered in a way of normal circulation in drilling process, which is easy to bring about “sand sticking” and to lower working efficiency.